1. Field of the Invention
The present invention relates to a driven wheel torque control system including a slip-reduction output torque control means for adjusting an output torque from a prime mover, of a vehicle, in accordance with the slipping state of a driven wheel driven by the prime mover in order to reduce an excessive slipping of the driven wheel.
2. Description of the Prior Art
There is conventionally known a so-called traction control system which assists the driving operation, on a snow-laden road or an iced road having a small road surface frictional coefficient, by controlling the output from an engine, which is a prime mover, to increase or decrease such output in accordance with the slipping state of a driven wheel generated upon acceleration of the vehicle (for example, see Japanese Patent Application Laid-open No. 8839/92).
However, in the vehicle equipped with such a traction control system, when a driven wheel is brought into a slipping state, the output from an engine is controlled to decrease such output regardless of a driver's will. Therefore, it is difficult for the driver to consciously cause slipping of the driven wheel to provide sporty driving. In addition, when driving on a road having a very small road surface frictional coefficient, only several % to several tens % of the output from the engine is transmitted. For this reason, the traction control device is operated only by slightly depressing an accelerator pedal and, therefore, the output from the engine is controlled to be decreased. Therefore, on a road surface having a small frictional coefficient, a range of the accelerator pedal through which a driver can consciously control the output from the engine is extremely small. Thus, it is difficult to control the accelerator pedal in such small range to provide a delicate slipping state.